With development of technologies, in technologies such as a sparse code multiple access (SCMA) technology or an orthogonal frequency division multiplexing (OFDM) technology, a plurality of terminal devices are allowed to share a same time-frequency resource for data transmission. That is, a transmitting device may perform coding and modulation on a to-be-transmitted stream of bits to generate a modulation symbol sequence, and send the modulation symbol sequence to a receiving device by using an air interface.
Currently, a multiple-input multiple-output (MIMO) technology is known, that is, the transmitting device and the receiving device may transmit data through a plurality of antenna ports, so as to improve a system capacity and transmission reliability. Therefore, it is expected to combine the multiple-input multiple-output technology with a multiplexing technology such as the sparse code multiple access technology or the orthogonal frequency division multiplexing technology, so as to further improve performance of a communications system.
How to combine the multiple-input multiple-output technology with the technology such as the sparse code division multiple access technology to improve system capacity and transmission reliability to the greatest extent is a problem that needs to be resolved urgently.